Aetheris

An Ioun stone is named after Ioun, a god of knowledge and prophecy revered on some worlds. Many types of Ioun stone exist, each type a distinct combination of shape and color. When you use an action to toss one of these stones into the air, the stone orbits your head at a distance of 1d3 feet and confers a benefit to you. Thereafter, another creature must use an action to grasp or net the stone to separate it from you, either by making a successful attack roll against AC 24 or a successful DC 24 Dexterity (Acrobatics) check. You can use an action to seize and stow the stone, ending its effect. A stone has AC 24, 10 hit points, and resistance to all damage. It is considered to be an object that is being worn while it orbits your head. ***Mastery.*** Your proficiency bonus increases by 1 while this pale green prism orbits your head.